The present invention relates to a machine for assembling a magnetic latch assembly. More particularly, the present invention relates to a multi-station machine for assembling a single point magnetic contact latch assembly, such as the assembly disclosed in U.S. Pat. No.5,343,346, that includes a core with an annularly shaped flange and chamfered pin (hereinafter collectively referred to as "the post"), a magnet, and a casing, the magnetic latch assembly being mounted on a crash stop.
The single point magnetic contact latch assembly has several small components that can be manually assembled together. However, there are problems associated with such manual assembly. For example, the casing which covers the magnet must be press-fitted on the flange of the post with a force sufficient to outwardly radially deform the casing onto the flange so that the casing is secured thereto. An insufficient force will not properly secure the casing to the flange. Components of the latch assembly could thus fall off and potentially damage the hard drive. In addition, if the casing is improperly aligned on the flange, the end of the core which provides the single point of contact may be completely or partially inaccessible to a metal tang portion attached to a read/write arm of the disk drive. Such improper alignment could result in inability to secure or "lock" the read/write arm of the hard drive. Other potential assembly problems may arise during the mounting of the pin of the post to the crash stop. The pin must be properly aligned and secured to the crash stop so that the metal tang portion attached to the read/write arm can be captured by the end of the core. In addition, excessive force applied when mounting the pin to the crash stop may cause stress fractures in the crash stop either destroying it or weakening its structural integrity. Yet another problem associated with manual assembly of the latch is contamination that may result from handling by one or more people. The completed assembly must be as free as possible from particulate matter, dirt, or oils which can interfere with such things as the magnetic medium or read/write head(s) of the disk drive assembly. A further problem associated with manual assembly is the large amount of time required to assemble a single completed magnetic latch assembly and attach it to a crash stop.
A machine for assembling the single point magnetic contact latch assembly and for attaching the assembly to a crash stop that solved the above problems would be a welcome improvement. Such a machine could provide a higher degree of consistency of assembly not available with manual assembly. In addition, higher throughput could be achieved. Such advantages would result in a cost savings because of reduced labor required, fewer parts wasted, and less hard drives damaged.
Accordingly, the present invention includes a machine for assembling a magnetic latch assembly having components that include a post, a magnet, and a casing. The machine includes structure for placing and securing the post in a preferred orientation during assembly of the magnetic latch assembly. First structure is provided for assembling the magnet adjacent a core portion of the post. Second structure is provided for assembling the casing over the magnet and the core portion. Structure is further provided for removing the assembled magnetic latch assembly from the placing and securing structure. In one embodiment, the post placing and securing structure includes a gripper assembly. The gripper assembly may include a fixed jaw having a notch formed therein and a movable jaw, a surface of which adjacent the fixed jaw tapers to define, in cooperation with the notch, an opening to receive the pin portion. Structure for biasing the movable jaw is provided as well as structure for mounting the fixed and movable jaws and the biasing structure to the machine. The movable jaw may have a substantially flat surface formed thereon that is engaged by an actuator that displaces the movable jaw in a direction against the bias of the biasing structure so that the pin portion of the post is insertable and releasably secured between the jaws. The fixed and movable jaws may be formed from 300 series stainless steel that is coated with titanium nitride. Adjacent surfaces of the jaws may include wear-resistant inserts. The wear-resistant inserts may be made from carbide material. The biasing structure may include a spring disposed in a groove formed in the movable jaw. The mounting structure may include a two-piece housing.
The post placing and securing structure may include a first pick-and-place assembly having an end effector thereon. The post placing and securing structure may further include a vibratory feeder bowl having a plurality of posts therein, an in-line feeder, and a dead nest for supplying a single, properly oriented post to the end effector. The post placing and securing means may also further include an overload assembly mounted in the first pick-and-place assembly for alerting an operator of the machine when the end effector attempts to place the post in the securing structure when another post is already there.
The first structure for assembling the magnet adjacent a core portion of the post may include a second pick-and-place assembly having an end effector thereon. The first structure may further include a vibratory feeder bowl having a plurality of magnets therein, an in-line feeder, and a dead nest for supplying a single, properly oriented magnet to the end effector. The first means may further include an overload assembly mounted in the second pick-and-place assembly for alerting an operator of the machine when the end effector attempts to place the magnet over the core when another magnet is already there.
The second structure for assembling the casing over the magnet and the core portion may include a second pick-and-place assembly having an end effector thereon. The machine may further include a ram that engages a plunger assembly of the second pick-and-place assembly that provides a force to press-fit the casing on an annular flange of the post. The second structure may further include a vibratory feeder bowl having a plurality of casings therein, an in-line feeder, and a dead nest for supplying a single, properly oriented casing to the end effector. The second structure may further include an overload assembly mounted in the second pick-and-place assembly for alerting an operator of the machine when the end effector attempts to place the casing over the magnet and the core portion when another casing is already there.
The removing structure may include a first pick-and-place assembly having an end effector thereon. The end effector may include a punch. The removing structure may mount the magnetic latch assembly to a crash stop. The machine may include a ram that engages a plunger assembly of the removing structure to provide a force to press-fit the magnetic latch assembly to the crash stop. The machine may further include structure for securing the crash stop during mounting of the magnetic latch assembly to the crash stop by the removing structure. The crash stop securing means is mounted to the machine.
The crash stop securing structure may include a base having a generally flat portion and a generally upright portion and structure for mounting the crash stop to the base. The crash stop securing structure also includes structure attached to the base for supporting a heel portion of the crash stop. The crash stop securing structure further includes structure formed in the upright portion of the base for facilitating alignment of the crash stop on the base prior to attachment of an assembled magnetic latch assembly to the crash stop. The mounting structure may include a clamp pin mounted in the generally flat portion of the base so as to extend substantially orthogonally from the flat portion of the base and through an opening formed in the crash stop. The mounting structure further includes structure for biasing the clamp pin so that, when the clamp pin is moved against the direction of the bias thereon, it exerts a force on the crash stop that secures the crash stop to the base. The biasing structure may include an O-ring that is disposed in the base so as to surround a peripheral portion of the clamp pin. The alignment facilitating structure may include a groove formed in the upright portion of the base. The supporting structure may include a locator pin driven in the generally upright portion of the base. The locator pin has a substantially flat top surface that extends above the flat portion of the base and abuts against a heel portion of the crash stop. Portions of the base may be recessed so as to provide clearance for an end effector used to place the crash stop onto and remove the crash stop and attached magnetic latch assembly from the crash stop securing structure.
The removing structure may further include an overload assembly mounted in the first pick-and-place assembly for alerting an operator of the machine when the end effector attempts to mount the magnetic latch assembly to the crash stop when another magnetic latch assembly is already there.
The machine may have multiple stations for progressively assembling the magnetic latch assembly. These stations may include a post placement station, a magnet placement station, a casing placing station, and a removal station. The machine may further include a first indexing turntable on which a portion of the post placing and securing structure is mounted. The first indexing turntable advances components of the magnetic latch assembly to the stations of the machine. There may be a plurality of post placing and securing structures mounted on the first indexing turntable at the stations of the machine so that a plurality of magnetic latch assemblies can be simultaneously assembled by the machine.
The machine may further include a crash stop assembly station for mounting the magnetic latch assembly to a crash stop. The crash stop assembly station may include a second indexing turntable and structure for securing the crash stop mounted thereon.
The machine may further include a crash stop removal station for removing the crash stop and mounted magnetic latch assembly from the crash stop securing structure. The second indexing turntable advances the crash stop and the mounted magnetic latch assembly from the crash stop assembly station to the crash stop removal station. The crash stop removal station may include a hand-and-gripper assembly.
The machine may further include a crash stop placement station for placing the crash stop on the crash stop securing structure. The second indexing turntable advances the crash stop from the crash stop placement station to the crash stop assembly station. The crash stop placement station may include an actuator mechanism for placing a crash stop on the crash stop securing structure, a vibratory feeder bowl having a plurality of crash stops therein, an in-line feeder, and a dead nest for supplying a single properly oriented crash stop to the actuator mechanism.
The machine may include a magnetization station having structure for magnetizing the magnet subsequent to placing the casing thereover. The machine may further include a magnetization verification station having structure for verifying that the magnetic field strength of the magnetized magnet of the magnetic latch assembly is within a predetermined range of values. The verifying structure alerts an operator of the machine if the magnetic field strength of the magnetized magnet is outside of the predetermined range. The verifying structure may include a Hall effect sensor.
The machine may include a vacuum station having structure for removing particulate matter from the magnetic latch assembly subsequent to placement of the casing over the magnet and the core.
The invention also includes a method of assembling a magnetic latch assembly having components that include a post, a magnet, and a casing. The steps of the method include grasping and securing the post in a preferred orientation, grasping a magnet in a preferred orientation, placing the magnet over a core portion of the post, grasping a casing in a preferred orientation, placing the casing over the magnet and core, and press-fitting the casing to secure the casing to a portion of the post to thereby form the magnetic latch assembly. The method may also include the step of press-fitting the magnetic latch assembly to a crash stop. An additional step of magnetizing the magnet subsequent to press-fitting the casing to the portion of the post may also be part of the method. The method may further include the step of verifying the magnetic field strength of the magnet subsequent to the step of magnetizing the magnet. A step of removing particulate matter subsequent to pressing the casing to the portion of the post may also be part of the method.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.